Can Someone Guess My Crypto Private Key?

In this video, Bitcoin educator and entrepreneur Andreas M. Antonopoulos explains why it's basically impossible for someone to just guess the private key to unlock your bitcoin, ethereum, or other cryptocurrency.

Timestamps:

0:00 Introduction — What is Down the Rabbit Hole?
1:22 Can someone guess my bitcoin, ether, or another crypto asset private key?
2:28 What is a crypto private key?
2:58 A crypto private key is a long number but how long is it exactly?
3:50 What is 2 to the 256?
5:00 Unfathomably big numbers!
8:00 Molecules and sand!
13:00 Eddington

Private keys that control cryptocurrencies are taken from a large number set. A really large number set. So large, in fact, that it's almost impossible for most of us to understand how large it is. Which makes it hard for us to understand why someone can't just guess our private key.

This question is from the October Open Topic Livestream Q&A, which took place on October 24th, 2020.